Bart C Weimer

Publications (65) View all

• Article: Microbial biodiversity of Great Salt Lake, Utah

  Bart Weimer, Giovanni Rompato, Jacob Parnell, Reed Gann, Balasubramanian Ganesan, Cristian Navas, Martin Gonzalez, Mario Clavel, Steven Albee-Scott
  Natural Resources and Environmental Issues. 01/2009; 15(1).
• Chapter: Gene Expression Arrays in Food

  Bart Weimer, Yi Xie, Lan-szu Chou, Adele Cutler
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  ABSTRACT: Gene expression in microbes can be detected with an oligonucleotide-based DNA macroar-ray. The DNA macroarray is composed of short (22-24-mer) oligonucleotide probes immobilized onto a nylon membrane via polyinosine tails. An indirect high-density labeling method was used to effectively incorporate biotin into the nucleic acids. The hybridization signals were detected with a chemiluminescence-based method and digitized with a desktop scanner. The utility of this protocol was demonstrated by profiling the expression of 375 metabolically related genes in Lactococcus lactis ssp. lactis IL1403 during heat, acid, and osmotic stresses. The macroarray accurately detects known stress responses in lactococci. Additionally, expression profile changes of a commercial starter during cheddar cheese ripening can also be profiled. Key WordsGene expression–DNA macroarray–DNA microarray–expression arrays–metabolomics–functional genomics–amino acid metabolism–peptide hydrolysis
  05/2008: pages 333-343;
• Article: A novel approach to identify bovine sperm membrane proteins that interact with receptors on the vitelline membrane of bovine oocytes

  B. J. Pate, K. L. White, D. Chen, K. I. Aston, B. R. Sessions, T. D. Bunch, B. C. Weimer
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  ABSTRACT: At fertilization, the sperm triggers intracellular calcium oscillations, which are pivotal to oocyte activation and development. A working hypothesis for the interaction between the sperm and the oocyte is that disintegrin ligands on the inner acrosomal membrane of the sperm bind to integrin receptors on the oocyte vitelline membrane. The aim of these experiments was to find and identify the sperm protein ligands involved in bovine sperm-oocyte interactions. In situ fluorescent labeling of proteins and 2-D gel electrophoresis were used to identify specific sperm membrane proteins that interact with proteins in the oocyte vitelline membrane. Sperm were labeled with a fluorescent dye and used to fertilize zona-free oocytes. Sperm-oocyte complexes were either lysed immediately, or following covalent cross-linking of proteins with dibromobimane. The cross-linking reagent serves the critical function of covalently linking proteins together so that they will remain as a unit through lysis of the cells and 2-D gel analysis, and which can be subsequently identified by mass spectrometry. Lysates were electrophoretically run on the same 2-D gel. The comparison of uncross-linked and cross-linked protein spots revealed that some proteins shifted position based on binding. These spots were picked and proteins identified by mass spectrometry. These results provide a list of specific sperm proteins that interact with oocyte membrane proteins and establish a group of candidate ligands, one or more of which may be responsible for induction of outside-in signaling resulting in oocyte activation and fusion of the gametes.
  Molecular Reproduction and Development 05/2008; 75(4):641-9. · 2.53 Impact Factor
• Article: A SEMI‐AUTOMATED COLORIMETRIC METHOD FOR DETERMINATION OF AMINOPEPTIDASE ACTIVITY IN TURBID SOLUTIONS 1

  BENJAMIN DIAS, BART WEIMER
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  ABSTRACT: ABSTRACTA semi-automated colorimetric method to measure aminopeptidase activity using reflectance colorimetry is described. p-Nitroanilide derivatives of 12 amino acids were used to detect aminopeptidase activity in phosphate buffer and milk. Enzyme activity, in phosphate buffer, determined using spectrophotometry and colorimetry, was linearly correlated (R2= 0.991), indicating colorimetry can be used in place of spectrophotometry to measure aminopeptidase activity. Aminopeptidase activity determined colorimetrically in buffer was linearly correlated (R2= 0.981) with activity in milk, indicating colorimetry can be used to detect enzyme activity in turbid solutions such as milk and dairy products. Optimum substrate concentration differed for milk and phosphate buffer. Assays in milk required higher concentrations of chromogenic substrates (0.8–1.0 mM), than did assays in phosphate buffer (0.3–0.5 mM). The assay was more repeatable in milk (average coefficient of variation = 3.6%) than in buffer (average coefficient of variation = 14.0%). Aminopeptidase activity of cell free extracts from Lactobacillus helveticus CNRZ32 were used to demonstrate the use of the assay. Enzyme profiles of this strain were similar in milk and in phosphate buffer. High activity was detected with p-nitroanilide derivatives of arginine, lysine, leucine, alanine, and methionine.
  Journal of Rapid Methods & Automation in Microbiology 05/2007; 3(3):223 - 235. · 0.58 Impact Factor
• Article: Use of capillary electrophoresis and laser-induced fluorescence for attomole detection of amino acids.

  M Ummadi, B C Weimer
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  ABSTRACT: A capillary electrophoresis and laser-induced fluorescence (CE-LIF) method was developed to identify and quantitate at amol (10(-18)) concentration. Amino acids were derivatized with 3-(4-carboxybenzoyl)-2-quinoline-carboxaldehyde prior to CE-LIF analysis. The assay was developed by varying the sodium borate concentration, buffer pH, operating voltage, and operating temperature. A run buffer system containing 6.25 mM borate, 150 mM sodium dodecyl sulfate, and 10 mM tetrahydrofuran (pH 9.66) at 25 degrees C, and 24 kV provided analysis conditions for a high-resolution, sensitive, and repeatable assay of amino acids. The rate of derivatization, stability of the labeled amino acids, and amino acid quantitation varied for each amino acid. Amino acids were detected with greater efficiency by this method than automated HPLC amino acid analysis. The repeatability of the assay ranged from 0.3 to 0.9% within a day and 0.7 to 1.5% between analysis days. Bacterial amino acid utilization in a chemically defined medium was successfully monitored using this method. This work defines a sensitive and repeatable method for the detection of amino acids during bacterial metabolism.
  Journal of Chromatography 08/2002; 964(1-2):243-53. · 4.53 Impact Factor